Using the system("pause") command in C++

system("pause") command C++

In this article, we’ll take a look at using the system(“pause”) command in C++.

Before going through this article, note this the system("pause") command is only available in Windows Systems.

This means that you cannot use this from any Linux / Mac machine.

The system() command

Before going through the system(“pause”) command, let’s understand what system() does.

#include <cstdlib>

**int**` `**system**``(``**const**` `**char**` `*command);

The system() function performs a call to the Operating System to run a particular command.

Note that we must include the <cstdlib> header file.

This is very similar to opening a terminal and executing that command by hand.

For example, if you want to use the “ls” command from Linux, you can use system("ls").

If you are having any Linux/Mac machine, you can try the below code.

#include <iostream>

#include <cstdlib>

**using**` `**namespace**` `std;

**int**` `main() {

// Try the "ls -l" command from your Linux / Mac machine

**int**` `ret =` `**system**``(``"ls -l > test.txt"``);

**return**` `0;

`}`

Possible Output

total 16

-rwxr-xr-x 1 2001 2000 9712 Jun 25 21:11 a.out

-rw-rw-rw- 1 2001 2000  209 Jun 25 21:11 main.cpp

-rw-r--r-- 1 2001 2000    0 Jun 25 21:11` `test``.txt

Now that we’re a bit clear on what system() can do, let’s look at the system(“pause”) command.

#programming-c #cplusplus

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Using the system("pause") command in C++

Using the system("pause") command in C++

system("pause") command C++

In this article, we’ll take a look at using the system(“pause”) command in C++.

Before going through this article, note this the system("pause") command is only available in Windows Systems.

This means that you cannot use this from any Linux / Mac machine.

The system() command

Before going through the system(“pause”) command, let’s understand what system() does.

#include <cstdlib>

**int**` `**system**``(``**const**` `**char**` `*command);

The system() function performs a call to the Operating System to run a particular command.

Note that we must include the <cstdlib> header file.

This is very similar to opening a terminal and executing that command by hand.

For example, if you want to use the “ls” command from Linux, you can use system("ls").

If you are having any Linux/Mac machine, you can try the below code.

#include <iostream>

#include <cstdlib>

**using**` `**namespace**` `std;

**int**` `main() {

// Try the "ls -l" command from your Linux / Mac machine

**int**` `ret =` `**system**``(``"ls -l > test.txt"``);

**return**` `0;

`}`

Possible Output

total 16

-rwxr-xr-x 1 2001 2000 9712 Jun 25 21:11 a.out

-rw-rw-rw- 1 2001 2000  209 Jun 25 21:11 main.cpp

-rw-r--r-- 1 2001 2000    0 Jun 25 21:11` `test``.txt

Now that we’re a bit clear on what system() can do, let’s look at the system(“pause”) command.

#programming-c #cplusplus

Annalise  Hyatt

Annalise Hyatt

1594449240

Bash add pause in shell script with bash pause command

ost of you may be aware of old good DOS/2000/XP pause command. It is used to display the prompt while suspending the processing of a batch script. It is used within a computer batch file and allows the computer to pause the currently running batch file until the user presses any key. Let us see how to pause our bash based shell script for a given number of times in seconds/minutes/hours before continuing to next operation/command running on a Linux or Unix-like systems.

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bash pause command under Linux / UNIX / macOS

There is no pause command under Linux/UNIX bash shell. You can easily use the read command with the -p option to display pause along with a message.

Bash add pause prompt using sleep and read command in shell scripts under Linux and Unix

Bash add pause prompt in a shell script with bash pause command

For example:

read -p "Press [Enter] key to start backup..."
read -p "Press any key to resume ..."
## Bash add pause prompt for 5 seconds ##
read -t 5 -p "I am going to wait for 5 seconds only ..."

#bash #pause #linux #unix

What Is System("pause") and Why Is It Considered A BAD PRACTICE? C++ Programming Common Questions

What is system(“pause”) and why is it considered bad practice?
In this video, I’ll teach you how to pause your C++ console before it closes so that you can read the output in the console.
I’ll explain three different ways to do this, and teach you about the system(“pause”) command and the problems that can occur if you use it.

Contents:

  • 00:00 - What is system(“pause”), and why is it considered bad practice?
  • 06:32 - Pause C++ Console App using cin.get()
  • 08:06 - Pause C++ Console App with breakpoints
  • 10:37 - Pause C++ Console App with Visual Studio “Start without debugging” option

#cplusplus

Linux Sleep Command (Pause a Bash Script)

sleep is a command-line utility that allows you to suspends the calling process for a specified time. In other words, the sleep command pauses the execution of the next command for a given number of seconds.

The sleep command is useful when used within a bash shell script, for example, when retrying a failed operation or inside a loop.

In this tutorial, we will show you how to use the Linux sleep command.

How to Use the sleep Command

The syntax for the sleep command is as follows:

sleep NUMBER[SUFFIX]...

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The NUMBER may be a positive integer or a floating-point number.

The SUFFIX may be one of the following:

  • s - seconds (default)
  • m - minutes
  • h - hours
  • d - days

When no suffix is specified, it defaults to seconds.

When two or more arguments are given, the total amount of time is equivalent to the sum of their values.

#sleep #linux sleep #bash script #bash

Archie  Clayton

Archie Clayton

1588488960

How to use the JavaScript Equivalent of Sleep, Wait, Delay, and Pause

JavaScript is the language of web. JS hasn’t been the same since ES5 was released. More and more ideas and features are being ported from different languages and being integrated in JavaScript. One such feature is Promises, which is probably the most widely used thing in JavaScript after ES5 was released.

But one of the things which JavaScript miss is the way to “pause” execution for a while and resume it later. In this post, I’ll discuss how you can achieve that and what it really means to “pause” or “sleep” in JavaScript. Spoiler: JavaScript never really “pauses”

TL;DR

Here’s the copy-pasta code which would do the job:

/**
 * 
 * @param duration Enter duration in seconds
 */
function sleep(duration) {
	return new Promise(resolve => {
		setTimeout(() => {
			resolve()
		}, duration * 1000)
	})
}

But what is really happening here?

setTimeout and the fake Promises

Let’s see a quick example using the above snippet (we’ll discuss what’s happening in it later)

async function performBatchActions() {
	// perform an API call
	await performAPIRequest()

	// sleep for 5 seconds
	await sleep(5)

	// perform an API call again
	await performAPIRequest()
}

This function performBatchActions, when called, would simply execute the performAPIRequest function, wait about 5 seconds, and then call the same function again. Note how I wrote about 5 seconds, and not 5 seconds.

A strong note to put out here, the above code does not guarantee a perfect sleep. It means that if you specify duration to be, say 1 second, JavaScript does not guarantee that it would start running the code after the sleep exactly after 1 second. Why? You may ask. Unfortunately, that’s because timers work in JavaScript, and in general, event loop. However, JavaScript absolutely guarantees that the piece of code after the sleep would never execute before the said time, so we don’t really have a full indeterminate situation, just a partial one, and in most cases, within a margin of a few milliseconds only.

JavaScript is single threaded

A single thread means JavaScript process cannot really go out of the way at all. It has to do all the things - from event listeners, to HTTP callbacks, on the same main thread. And when one thing is executing, another one cannot execute. Consider a webpage in which you have multiple buttons and you run the code above to simulate a sleep for lets say 10 seconds. What do you expect would happen?

Nothing at all. Your webpage would work just fine, your buttons would be responsive, and once the 10 second sleep is done, the code next to it would execute. So it’s evident that JavaScript did not really block the whole main thread because if it did that, your webpage should have frozen and the buttons should have become non-clickable. So how did JavaScript actually pause a single thread, without ever really pausing it?

Meet the Event Loop

Unlike other languages, JavaScript doesn’t just keep on executing code in a linear fashion from top to bottom. It is an asynchronous event driven language with tons of magic in the form of event loop. Event loop splits your code in synchronous and certain events - like timers and HTTP requests. Precisely speaking, there are two queues - task queue and microtask queue. Whenever you run JS, and there’s an asynchronous thing (like a mouseclick event, or a promise) JavaScript throws it in the task queue (or microtask queue) and keeps executing. When it completes a “single tick” - it checks if task queues and microtask queue has some work for it. If yes, then it’ll execute the callback/perform an action.

I would really recommend anyone interested in deep working of event loop to watch this video:

Conclusion

You came here for a simple sleep instruction in JavaScript, ended up learning about one of the core things in JavaScript - event loop! Amazing, isn’t it?

Originally published by Mehul Mohan at https://www.freecodecamp.org

#javascript #web-development